1. Field of the Invention
This invention relates to a zinc dust containing slurry and a water coating material, particularly to a basic technique for manufacturing a water zinc rich paint.
2. Description of the Related Art
Paints utilizing sacrificial anticorrosion function of zinc on iron are widely used as a zinc rich paint. However, most of them contains organic solvent and have a problem in that they have a bad influence on the environment. On the other hand, water zinc rich paints have a problem in that they generate hydrogen gas in mixing zinc and water and in that they are inferior in antirust capability. Zinc rich paints containing chromic acid as a binder are widely used, too. However, there is also a problem that, since they contain chrome, they have a bad influence on the environment.
As described above, practical zinc rich paints contain the organic solvent or the chrome and are problematic in that they have a bad influence on the environment. On the other hand, the water zinc rich paints are not suitable for practical use at present. As a manufacturing method of a water zinc rich paint, Japanese Laid Open Patent Application No. 6-9897 discloses a method for covering zinc containing metal flakes with colloidal silica coating. However, the colloidal silica has high degree of polymerization and globular structure. Consequently, the colloidal silica becomes bulky and is not capable of forming a dense coating on a surface of zinc. Moreover, the colloidal silica is deficient in preventing the water from contacting with OH— (OH minus) ions. Furthermore, there is disadvantage that use of the colloidal silica causes increase of costs.